This invention relates to loading dock technology. In particular, it relates to a safety gate which is placed at loading dock openings to prevent vehicular or foot traffic from falling off the end of the dock and to prevent injury.
Doors of a loading dock are often left in the opened position either for purposes of ventilation or because of the frequency of use of the dock makes closing the door inconvenient. Such loading docks are generally equipped with dock levelers, many of the pit type which when stored in a cross-traffic position allow forklift trucks and workers to traverse laterally across the pit area. When no trailer is parked at the door, there is a possibility that a forklift truck while maneuvering between other doors or aisles can accidentally be backed or driven through an open doorway or fall off the dock into the driveway below. Similarly, a pedestrian walking near a doorway could accidentally step over the edge.
Within loading dock and material handling technology, a number of devices are presently in use which partially address this problem. However, they have several significant deficiencies. One group of technology extends the lip of the dock leveler above dock level in the stored or cross traffic position. The purpose is to erect a barrier at floor level which will prevent a forklift truck from backing or otherwise driving over the edge. Typical of these devices are those found in U.S. Pat. Nos. 4,920,598 and 5,040,258. The devices disclosed therein are derivatives of the so-called "Post Office Lip". In general, the concept is to have a lip which extends above the dock floor when the dock leveler is in the stored, cross traffic position. However, when the dock leveler is actuated and the lip extended, the barrier retracts to thus allow traffic to move in an unimpeded manner over the leveler.
While these devices may serve to prevent a vehicle from rolling off the dock, in actuality it compromises overall dock safety because a pedestrian has to deal with a newly created tripping hazard. That is, these lip extensions are generally fairly low and even if visibly marked extend to a height above the dock which causes a stumbling point for a pedestrian. Moreover, such devices are also pinched-points should the dock leveler require manual intervention in order to actuate and fully raise the lip. Finally, such devices prevent an end-loading operation below dock level.
Moreover, such devices define a rigid barrier with little to no deflection to provide energy absorption. For example, if a forklift truck traveling at 5 miles per hour strikes a barrier which deflects minimally, for example, 0.5 inches the deceleration will be in the order of 18G. A forklift truck typically weighs about 10 thousand pounds and the force of impact would be over 180 thousand pounds exerted against the lip of a dock leveler. Even if this force would not damage the dock leveler itself, the forklift truck or the cargo would be subjected to high deceleration, and could result in serious injury to the forklift truck driver.